Transparent Photochromic Wood Composites Incorporating AgBr Nanoparticles for UV-shielding Applications

Transparent wood(TW)is a wood-based biomaterial with several advantages,such as high optical transmittance,low thermal conductivity,and tunable haze.TW is functionalized according to its transparency to broaden its applications in different fields.Several studies have examined wood functionalization in recent years;however,few studies have reported photochromic TW(PTW)for ultraviolet(UV)-shielding window applications.Herein,PTW was obtained by infiltrating the delignified wood template with photochromic silver bromide(AgBr)nanoparticles and a pre-polymerized methyl methacrylate(MMA)mixture solution.The obtained PTW can adjust the luminous flux on change in the color in the visible light region.The photochromic properties were examined,and the optical properties of the composites were characterized using UV-Vis spectrophotometry.Light transmittance of PTW was up to 86.5%at 800 nm before UV irradiation,and it decreased to 70.1%at 800 nm after UV irradiation,as the wood color changed from colorless to dark purple under UV irradiation.Thus,this work not only achieves high-value utilization of wood,but also produces a new material that can be used in varied fields,such as UV-shielding,energy saving,and smart building.

UV-Shielding and Catalytic Characteristics of Nanoscale Zinc-Cerium Oxides

Fine particles of zinc-cerium oxides （ZCO） used as an ultraviolet filter were prepared via combustion synthesis route. The catalytic activity, UV-shielding performance, surface modification and application of ZCO in polyester varnish were discussed in detail. The experimental results indicate that the photo-catalytic activity of ZCO is much smaller than these of ZnO and TiO2; the oxidation catalytic activity of ZCO is far lower than that of CeO2; the ZCO has shown excellent ultraviolet absorption in the range of UV; addition modified ZCO （MZCO） into polyester will enhance the UV-shielding capability of polyester.

Adsorption of avermectins on activated carbon: Equilibrium, kinetics, and UV-shielding

The adsorption of biopesticide avermectins onto activated carbon from ethanol solution with different initial concentrations at 303.15 K was performed. The obtained equilibrium and kinetic data of the adsorption process were assayed to evaluate the adsorption potential of activated carbon for avermectins. The results show that the activated carbon is effective for the adsorption of avermectins. Moreover, the adsorption of avermectins onto activated carbon agrees with Langmuir isotherm model, while pseudo-second-order kinetics model is better fitable for such adsorption process. In addition, activated carbon can efficiently protect adsorbed avermectins from photodegradation.

Study on the Application of Luminescent Bacteria to the Evaluation and Analysis of the UV-shielding Property of Nanooxide

In this paper, it was found that luminescent bacteria could be killed by UV light and the bioluminescence intensity would be decreased. With the protection of nanooxide, the decrease of the bioluminescence could be supressed, therefore luminescent bacteria could be utilized to analyze and evaluate the UV-shielding property of nanooxide. Vibrio-qinghaiensis Q67, a kind of luminescent bacteria, was used here to study the influence of different kinds and concentrations of nanooxide on the luminescence intensity of bacteria, which were illuminated by UVA, UVB or UVC light, respectively. A method was established according to the relative value of the decrease of the luminescence intensity, which can be used to analyze and evaluate the UV-shielding property of nanooxide against UVA, UVB or UVC light, respectively. It also provided an effective way to analyze and evaluate the UV-shielding property of sunscreen for cosmetic and other industries.

Wood By-Products as UV Protection:A Consequence Review

In recent decades,the ozone layer has suffered considerable damage,increasing the entry of ultraviolet(UV)light into the atmosphere and reaching the earth’s surface,negatively affecting life.Accordingly,researchers aimed to solve this problem by synthesizing advanced UV-shielding materials.On the other hand,developing an easy and green strategy to prepare functional materials with outstanding properties based on naturally abundant and environmentally friendly raw materials is highly desirable for sustainable development.Because biomass-derived materials are sustainable and biodegradable,they present a promising substitute for petroleum-based polymers.The three main structural constituents of the plant biomass-based materials that are naturally available are cellulose,hemicellulose,and lignin.This review details current developments using wood-based products such as cellulose,hemicellulose,and lignin in UV-shielding applications.It will start with assembling the structure and chemistry of cellulose,hemicellulose,and lignin,followed by their contributions to preparing UV-shielding materials.Finally,it will briefly discuss the different processing methods for the design of UV-shielding materials.The wood by-products offer additional opportunities to use the whole tree harvest.

Structural,morphological,optical and antibacterial performances of rare earth(Sm)-doped ZnO nanorods

The significant rise of ultra-violet(UV) radiation and pathogenic infectious bacteria poses a serious threat to global health.Numerous researchers' interests are attracted by novel materials with strong UVblocking ability,antibacterial activity and low toxicity to other species.In this case,a simple wet chemical method with different annealing temperatures(400,500,and 600℃) was employed to create highly effective rare earth(Sm)-doped ZnO nanorods.The(101) plane of wurtzite ZnO shifts towards a lower angle with increasing annealing temperature,according to the X-ray diffraction(XRD) study findings,which additionally establishes the consequence of lattice expansion.Occurrence of doublet peaks of Sm 3d(Sm 3d_(5/2) and Sm 3d_(3/2)) in the X-ray photoelectron spectroscopy(XPS) spectrum clearly validates the substitution of Sm^(3+) ions in the 500℃-annealed samples.The 500℃-annealed nanorods exhibit combined performances of the wide band gap,improved UV absorbance,and vivid green luminescent emission(563 nm).Additio nally,the nanorods have favorable UV-blocking execution of 96% for UVA at 360 nm,92% for UVB at 320 nm,and 57% for UVC at 225 nm,which is greater than the majority of ZnO-related materials that have been reported up to this date.Sm doping is also appropriate for improving bacterial inhibition against the two studied strains(Escherichia coli and Staphylococcus aureus),in addition to the intriguing features discussed above.Furthermore,with maximum inhibition zone diameters of 20±0.72 and 18±0.57 mm,respectively,these nanorods exhibit high inhibitory action against E.coli and S.aureus bacterial strains.The rare earth-doped material developed during the current experiment,which was annealed at 500℃,could potentially serve as an effective replacement for UV-blocking and antibacterial material,especially for biomedical applications.

Preparation and performance of CeO_2 hollow spheres and nanoparticles

CeO_2 hollow spheres were synthesized by polystryrene sphere（PS） templates and CeO_2 nanoparticles were prepared by a facile method. The as-obtained products were characterized by scanning electron microscopy（SEM）, N_2 adsorption-desorption, X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR） and UV-vis diffuse reflectance spectra. The results showed that the structure of the obtained CeO_2 hollow spheres was hollow microsphere with a diameter of 380 nm and the average particle size of CeO_2 nanoparticles was about 1700 nm. The two samples＇ Brunauer-Emmett-Teller（BET） surface area was 67.1 and 37.2 m^2/g. The CeO_2 hollow spheres had a better performance than nanoparticles at UV-shielding because of higher surface area and the structure of hollow sphere.

Transparent flexible ZnO/MWCNTs/PBMA ternary nanocomposite film with enhanced mechanical properties

Functional organic-inorganic nanocomposites with high transparency show significant potential application in many fields. However, it is still a great challenge to prepare flexible transparent nanocomposites due to the intrinsic stiffness of the nanoparticles and the poor interaction between nanopartieles and organic matrices. In this work, a transparent ternary nanocomposite film with enhanced mechanical performance is fabricated by two-steps. First, the transparent ternary ZnO/MWCNTs/n-butyl methacrylate （BMA） nanodispersion is prepared by mixing the ZnO/BMA and MWCNTs/BMA dispersions directly. Then, the ternary nanocoposites film is fabricated via in-situ bulk polymerization of the above nanodispersions. As a result, the tensile strength of the ZnO/MWCNTs/poly-n-butyl methacrylate （PBMA） ternary film is enhanced by 42% and the elongation at break is three times that of ZnO/PBMA nanocomposite. The hardness of the film increases from 5B to 1H with 40 wt% ZnO. These results indicate that ZnO and MWCNTs can improve the mechanical properties of the composite significantly. Importantly, the ternary nanocomposite film still remains high transparency and exhibit excellent UV-shielding performance. The as-prepared transparent multifunctional nanocomposite films have promising applications in optical materials and devices, such as optical filters, contact lenses and protection packing.

Synthesis and Characterization of SnO2-TiO2 Nanocomposite with Rutile-phase via Hydrothermal Method at Low Temperature

With Ti（SO4）2, SnC14-5H20 and urea as raw materials, SnO2-TiO2 nanocomposites were synthesized via low temperature hydrothermal method at 80--100℃ in aqueous solutions. The morphologies of the products were altered systematically by varying the Ti/Sn molar ratio of the reactants, and rutile-phase particles were obtained with an average diameter of about 52.2 nm at a molar ratio of Ti/Sn=7.5. The surface composition of the composite was revealed by X-ray photoelectron spectroscopy（XPS） and X-ray diffraction（XRD） to be solely TiO2 with a rutile structure. This new composite material exhibits a high ultraviolet absorption capacity, and its photocatalytic activity for phenol oxidation is much lower than that of the commercial titania nanoparticles（P25）.

Mitsunobu Functionalization of Poly(vinyl alcohol) Derivatives

Polymer functionalization is a powerful tool to prepare polymers with diverse structures without the need of synthesizing monomers or performing polymerization reactions.Polymers that are difficult to be synthesized using direct polymerization reactions can be accessed using polymer functionalization.We herein present Mitsunobu derivatization of poly(vinyl alcohol)(PVA)to convert the hydroxyl groups into diverse functional groups.